Enabling 3G service on US AT&T on unlocked iphone 4

[pacnorth206]

Hello,

I have an iphone 4 I bought in Japan:

Version: 4.3.3 (8J2)
Firmware: 04.10.1

I signed up for an AT&T account (with data plan) and got a sim card. Next, I bought a Gevey Ultra, cut my sim and did the manual unlock (dialing 112). It worked like a charm and now I can send texts and get AT&T signal, but without 3G.

I input the following entries into Settings>General>Network>Cellular Data Network>Cellular Data

APN: wap.cingular
User Name: WAP@CINGULARGPRS.COM
PW: CINGULAR1

I then powered off my phone and turned it back on. I went through the unlock process again (dialing 112) and the phone still shows full bars to AT&T, but without 3G.

I called AT&T, but they told me to turn on data roaming...

Is there a way to activate 3G service?

Also, the profile on my phone is still listed as my Japanese carrier (and is listed as UNSIGNED). Can I remove this profile?

Thanks for your help,
John

 

[Coleman2010]

I have an unlocked AT&T iPhone 4 and my settings are different and 3G works for me. They look like this:

Ceullar Data
ANP: phone
Username:
Password:

Visual Voicemail: acds.voicemail
Username:
Password:

Username and password for both are blank. I'm using a prepaid AT&T SIM with grand fathered unlimited data.